1. Field of Invention
This invention relates to silicone sealants which cure upon exposure to moisture without releasing corrosive by-products
2. Background Information
One of the types of one component room temperature curing silicone rubbers is that disclosed by Weyenberg in U.S. Pat. No. 3,334,067, issued Aug. 1, 1967. This composition of hydroxyl endblocked polydiorganosiloxane, silane of the formula R'Si(OR").sub.3 and chelated titanium compound is stable in the absence of moisture, but cures upon exposure to moisture. Compositions such as these have been developed into commercial sealants which are promoted for filling openings in buildings to seal them from the weather. A successful sealant for such applications must adhere to the substrate on which it is placed in order to form a reliable seal. Many different types of sealants have been made available with varying degrees of adhesion to various types of substrates such as are found in buildings. Improving the adhesion of such sealants to a wider variety of substrates has been the object of much experimentation.
UK Patent Application No. 2,137,217A published Oct. 3, 1984, discloses a self-bonding alkoxy-functional one-component RTV composition containing alkoxy terminated organopolysiloxane, a silane scavenger, a substituted guanidine curing accelerator, a condensation catalyst which includes titanium compounds, and an adhesion promoter having the formula (R.sup.1 OO).sub.3 --t(R.sup.1 1.sub.t)Si--Z where R.sup.1 O and R.sup.1 1 are monovalent hydrocarbon radicals having from 1 to 8 carbon atoms, t varies from 0 to 3 and Z is a saturated, unsaturated or aromatic hydrocarbon residue which may be further functionalized by a member selected from the class consisting of amino, ether, epoxy, isocyanato, cyano, acryloxy, and acyloxy, and multiples and combinations thereof. This invention is also covered by U.S. Pat. No. 4,483,973, issued Nov. 20, 1984.
U.S. Pat. No. 4,602,078, issued July 22, 1986, teaches a two part composition comprising the product obtained by mixing a silanol-terminated polydiorganosiloxane; a silicon compound having at least 3 silicon-bonded alkoxy or alkoxyalkoxy groups in the molecule; a metal or organometal salt of a carboxylic acid; a silane having silicon-bonded alkoxy or alkoxyalkoxy groups and a silicon-bonded group,--R' NHR, in which R' is alkylene and R represents H, alkyl or an aliphatic hydrocarbon group containing at least one amino group; and a silane having silicon-bonded alkoxy or alkoxyalkoxy groups and a silicone-bonded group containing an epoxy group. The composition cures upon mixing of the ingredients to an elastomer having improved adhesion.
Even though methods have been developed for producing improved adhesion of sealants to substrates, additional improvements are desired for increasing the number of substrates that can be successfully adhered by a single sealant to improve the versatility of the sealant.